This invention relates to a hydraulically driven cooling circuit for vehicle brakes. In particular, it deals with a hydraulic cooling circuit in a tractor scraper combination wherein hydraulic fluid is provided from one of the implement circuits in the scraper.
In heavy construction equipment, particularly those pieces of heavy construction equipment which are load carrying, cooling of vehicle brakes may be a necessity. Air cooling is practical in smaller comstruction vehicles in light of the size of the brakes. In larger vehicles, which utilize interleaved discs, one disc associated with a fixed portion of the vehicle while the next adjacent disc is associated with a traction member, air cooling usually is not sufficient. Accordingly, fluid may be supplied to an axial bore in the wheel axle and then through radiating ports in the shaft directed toward the interleaved discs. The hot cooling fluid leaving the brakes may then be pumped through a radiator for cooling and then back to the brakes.
In some cooling circuits attempts have been made to utilize the hydraulic fluid utilized by the vehicle implements. Although this is satisfactory, it suffers from a drawback that foreign particles may be picked up from the brakes and communicated back through the hydraulic system affecting high pressure seals, valves and orifices in the various implement subsystems. This can prove detrimental to the operation of such implements. Utilizing brake fluid suffers from the same drawback in that the brake fluid may pick up foreign particles from the brake linings thus affecting brake seals. Similarly utilizing lubrication fluid suffers from a similar drawback. Installation of appropriate filters can, in part, solve the problem, however such filters have to be changed frequently. Accordingly, it is appropriate to provide a separate fluid circuit for cooling of vehicle brakes. Separate fluid can not only be filtered but may also be chosen for its heat transfer properties.
In tractor-scraper combinations wherein the scraper is affixed to the tractor by an articulated connection, it is advantageous to limit the number of pressurized fluid lines passing over the articulated connection. Therefore to pressurize cooling fluid in the tractor for communication to a cooling circuit in the scraper would add at least two more lines (a supply and return line) passing over the articulated connection. It is therefore appropriate to utilize available hydraulic pressure to operate such a cooling circuit in the vicinity of the brakes themselves.
The operator of the heavy construction vehicle should be provided with the capability of actuating the brakes irregardless of the brake temperature. Frequently the operator's attention is concentrated on other functions in an operator actuated cooling system therefore overheated brakes and possibly a costly failure may be the result. It is therefore appropriate to relieve the operator of the added burden of watching brake temperature and provide temperature sensing means at the scraper brakes in a tractor scraper combination in order to actuate the cooling circuit motor.
Finally, it would be appropriate to design the primary hydraulic circuit so that upon actuation of a work implement no degradation of the work implement occurs because the cooling circuit is actuated.